The aforesaid lever arrangement for a microtome is used in particular in the context of a sliding microtome of the assignee, namely in the “Leica SM2000 R” model (see also FIG. 1). This sliding microtome is described in printed form in a company brochure of March 2003. In a sliding microtome, the knife that sections the specimen is moved back and forth on a movably arranged slide in order to section the specimen arranged in a specimen holder. The specimen holder is moved vertically onto the knife via a corresponding mechanism, namely a micrometer mechanism; this is also referred to as “advance.” The increment with which the specimen is advanced toward the knife can be set to an accuracy of 0.5 μm via a rotary knob fitted with a scale. Provided on the aforementioned sliding microtome as a further operating element is a crank with which a coarse drive mode for specimen movement toward the knife or away from the knife, i.e. substantially in a vertical direction, can be realized. It is possible as a result, after a sample change, to advance the specimen holder along with the specimen rapidly onto the knife, so that the sectioning operations with a definable desired cut thickness can directly follow one another. Provided as a further operating element is a lever (activation lever), guided in an elongated hole and provided with a knob, with which a manual advance motion of the specimen holder toward the knife can be activated. This knob or lever is usually utilized only in the context of advance in sectioning mode, the advance occurring with the increment currently set using the rotary knob fitted with the scale. The lever of this sliding microtome is movable in only one direction, specifically to the right for an operator located in front of the sliding microtome. This sliding microtome also encompasses an operating state with automatic advance, the operating element relevant thereto being arranged on the microtome slide. This automatic advance is usually utilized upon initial cutting of the sample, and replaces actuation of the activation lever.
The activation lever or the lever for manual advance, as well as the advance mechanism coupled thereto, is rotatable in only one direction. It may, however, be desirable to allow an advance of the specimen also to be produced with a rotation of the lever in the opposite direction, for example because different operators are operating a single sliding microtome, and one operator is left-handed and another operator right-handed. Such a requirement at present can be met only by making available two different sliding microtomes, specifically such that with the one sliding microtome a rotation of the lever to the right produces an advance, and with the other sliding microtome a rotation of the lever to the left likewise produces an advance. The rotation direction of the lever is therefore permanently defined in terms of the design.